In article , Larry Dighera
writes:

While the cost to operate the shuttles may be great, imagine the cost,
in today's dollars, to build a replacement and train the personnel.
Compared to the cost of operating existing shuttles, it would be many
times greater.

Blame it on NASA. If there is a lack of alternative "heavy lift" capability,
it's only because over 20 years ago, NASA mandated that all future government
payloads be designed around the shuttle, and all alternatives to the shuttle be
scuttled. This was in order to make the shuttle a "necessity" to America's
space program.

The reality was that the economics of the shuttle were complete fantasy, and
NASA knew it. (hence the mandates leaving the US with few alternatives until
the French, Russians, and Chinese started filling the void) We could (and
perhaps should have) gone on building disposable Saturn-like boosters (500k
pound payloads, vs the shuttle's 30k to 40k). The R&D was paid for, and the
support costs would be a fraction. (A typical shuttle mission costs somewhere
around half-a-billion)

John